Universal serial bus (USB) ports are presently included as standard equipment on personal computers and have become so widely used by various computer-related electronic devices that computer case manufacturers have begun including them in various positions, most typically at the front or side panel of a case, distal from where the motherboard is later installed. Cases equipped with these extra USB ports make use of a cable and connector(s) that are manually connected between the motherboard USB header and the port by the system builder. These connectors and ports are often not keyed to ensure that the connector is engaged with the port in the proper orientation to establish the proper connection of each contact of the port with the correct respective pin on the motherboard. As a result, it is possible that the builder may engage the connector with the port in a reverse orientation where the power supply and ground pins of the USB header are inadvertently connected to the ground and power supply contacts of the USB port respectively, the polarity of the USB port thereby being reversed from what it should be.
Connection of a peripheral device to a USB port improperly connected as described above can result in permanent and fatal damage to the motherboard, the USB port or the peripheral equipment connected thereto. A user having plugged in a USB device to a personal computer to discover that the device does not work thereafter may assume that the device is faulty and return the product for warranty service or discard it and purchase new equipment, not realizing that the problems resides in the computer and not the device being connected thereto.
Therefore, it would be desirable to have a polarity tester adapted for use with a computer's communication port to allow a user to test the polarity of the communication port before connecting peripheral equipment thereto.